Remedial actions for air flow errors in a fuel cell system

A method for operating a fuel cell stack of a fuel cell system in a vehicle, said method comprising:

• estimating a cathode air flow rate;
• detecting an error in the estimated cathode air flow rate;
• and
• utilizing high frequency resistance measurements from a high frequency resistance sensor to control a relative humidity of the fuel cell stack when the error in the estimated cathode air flow rate has been detected.

A system for operating a fuel cell stack of a fuel cell system in a vehicle, said system comprising:

• a controls unit that includes:
• means for estimating a cathode air flow rate;
• means for detecting an error in the estimated cathode air flow rate;
• and
• means for utilizing high frequency resistance measurements from a high frequency resistance sensor to control a relative humidity of the fuel cell stack when the error in the estimated cathode air flow rate has been detected.